全文获取类型
收费全文 | 1022篇 |
免费 | 36篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 36篇 |
妇产科学 | 16篇 |
基础医学 | 82篇 |
口腔科学 | 11篇 |
临床医学 | 45篇 |
内科学 | 254篇 |
皮肤病学 | 10篇 |
神经病学 | 36篇 |
特种医学 | 102篇 |
外科学 | 222篇 |
综合类 | 46篇 |
预防医学 | 83篇 |
眼科学 | 6篇 |
药学 | 28篇 |
肿瘤学 | 83篇 |
出版年
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 16篇 |
2017年 | 10篇 |
2016年 | 12篇 |
2015年 | 18篇 |
2014年 | 30篇 |
2013年 | 43篇 |
2012年 | 36篇 |
2011年 | 45篇 |
2010年 | 44篇 |
2009年 | 42篇 |
2008年 | 30篇 |
2007年 | 47篇 |
2006年 | 60篇 |
2005年 | 43篇 |
2004年 | 66篇 |
2003年 | 34篇 |
2002年 | 33篇 |
2001年 | 32篇 |
2000年 | 34篇 |
1999年 | 25篇 |
1998年 | 33篇 |
1997年 | 26篇 |
1996年 | 27篇 |
1995年 | 36篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 11篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 22篇 |
1988年 | 22篇 |
1987年 | 13篇 |
1986年 | 18篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1974年 | 2篇 |
1970年 | 3篇 |
1960年 | 1篇 |
1958年 | 2篇 |
1956年 | 1篇 |
排序方式: 共有1066条查询结果,搜索用时 15 毫秒
81.
Background
Despite its known advantages, breastfeeding rates are low world over. Large number of factors affect breastfeeding. This study was designed to detect maternal and neonatal factors that adversely affect breastfeeding in the perinatal period.Methods
A prospective, single-blinded study was conducted on randomly chosen mother-infant pairs in the maternity ward of a tertiary care service hospital. Only full term singletons born by normal vaginal delivery were studied. The B.R.E.A.S.T observation score and time spent by the infant at the mother''s breast were primary outcome variables. Maternal age, gravida, para status and education level were recorded. Birth weight, sex, gestation age of the infant and time interval from birth to observation were also recorded. Initial univariate analysis followed by multivariate analysis was performed using SPSS ver 7.5 software.Results
A total of 54 mother-infant pairs formed the study group; 19(35.2%) were primigravidas. Primigravidas status of the mother led to significantly lower scores (p<0.04; 95% CI 0.10 to 3.62) as did maternal age < 26 years (p<0.04; 95% CI 0.2. to 3.46) on univariate analysis. Low birth weight (<2500 g) was the only neonatal factor that significantly lowered breastfeeding scores (p<0.02;95%Cl 0.56 to 6.31). On multivariate analysis only primigravida status was significantly associated with lower scores (p<0.02). The alpha value of the study was 5% and the power was 74%. Time spent by infant on breast was not significantly different between primigravida and non-primigravida mothers.Conclusion
Primigravida status adversely affects breastfeeding scores; therefore counseling and support should be focused on this group. Extra care should also be taken to ensure adequate breastfeeding by younger mothers and in those with low birth weight infants. Larger studies with long-term follow up will be able to identify other factors and dertermine the effects of focused counseling and support in the perinatal period upon long-term breastfeeding rates.Key Words: Breastfeeding, Primigravida, Counseling 相似文献82.
Background
The present study was conducted to study the efficacy and toxicity profile of methotrexate chloroquine combination in treatment of active rheumatoid arthritis.Methods
24 patients of rheumatoid arthritis confirming to revised American Rheumatism Association (ARA) criteria were studied prospectively for twenty months. Clinical evaluation was made every 3 months. Clinical disease variables measured at each visit were number of joints with swelling, number of joints with tenderness and pain, duration of morning stiffness and physician and patient assessment of disease activity. Blood counts, liver function tests and other adverse effects due to drugs were monitored every 2 months.Results
10 patients demonstrated more than 50% improvement. 4 patients withdrew from study, 2 because of excessive nausea and vomiting and 2 because of noncompliance. Other side effects noted were hyperpigmentation, photosensitivity, skin rashes, raised transaminases and stomatitis.Conclusion
Methotrexate chloroquine combination has good efficacy and toxicity profile. Gastrointestinal side effects are most common and usually responsible for the discontinuation of the drugs.Key Words: Rheumatoid arthritis, Methotrexate, Chloroquine, Efficacy, Toxicity 相似文献83.
Gunn S Hashimoto S Karakozov M Marx T Tan IK Thompson DR Vincent JL 《Critical care (London, England)》2004,8(4):213-218
A young person presents with a highly malignant brain tumour with hemiparesis and limited prognosis after resection. She then suffers an iatrogenic cardiac and respiratory arrest that results in profound anoxic encephalopathy. A difference in opinion between the treatment team and the parent is based on a question of futile therapy. Opinions from five intensivists from around the world explore the differences in ethical and legal issues. A Physician-ethicist comments on the various approaches. 相似文献
84.
Engelbregt MJ van Weissenbruch MM Lips P van Lingen A Roos JC Delemarre-van de Waal HA 《BONE》2004,34(1):180-186
Undernutrition in early life may permanently change body structure, physiology and metabolism and leads to chronic diseases in later life. To test whether malnutrition during different critical time periods around birth in the rat has long-lasting effects on body composition and skeletal growth, we examined body weight and body composition in pubertal rats and adult rats of 6 months after pre- and postnatal malnutrition. Prenatal malnutrition or intra-uterine growth retardation (IUGR) was induced by ligation of the uterine arteries on day 17 of gestation and postnatal food restriction (FR) by litter enlargement to 20 pups per mother from day 2 after birth until weaning (day 24). Pubertal markers were balanopreputial separation (BPS) in the male and vaginal opening (VO) in the female. IUGR as well as FR resulted in a persistent growth retardation. From birth in IUGR rats and from day 4 after birth in FR rats until 6 months of age body weight in male and female rats was significantly lower compared with controls (P < 0.01 and P < 0.05). Although total body bone mineral content (TBBMC) did not differ between male IUGR rats and controls at BPS, at the age of 6 months TBBMC was significantly lower (P < 0.01) compared with controls. At BPS as well as at 6 months of age, TBBMC was significantly lower in male FR rats compared with controls (P < 0.05 and P < 0.01). In the female IUGR rats TBBMC was significantly lower compared with controls at VO (P < 0.01) and 6 months (P < 0.05). TBBMC in the female FR rats was significantly lower at VO (P < 0.01), but did not differ from controls at the age of 6 months. For both IUGR and FR male and female rats these differences disappeared after adjusting for body weight. Body composition in terms of total fat mass, percentage fat and percentage lean did not differ from controls in male and female IUGR rats at 6 months and the same results were observed in the female FR rats. However, in the male FR rats, total fat mass and percentage fat were significantly lower compared with controls (P < 0.01 and P < 0.05), while the percentage lean mass was significantly higher (P < 0.05). We conclude that different critical time periods of malnutrition around birth have different effects later in life on growth, which do not disappear at least after 6 months of life. With respect to body composition, only in the FR male rats, differences are found in total fat mass and the balance of percentage fat mass and lean mass. At time of puberty and at the age of 6 months bone mass adjusted for body weight does not seem to be affected by perinatal undernutrition. 相似文献
85.
86.
Lips P 《The New England journal of medicine》2003,348(4):347-349
87.
Physicians must be aware of histories, behaviours and physical findings of maltreated children. We report two cases of physical child abuse in which the initial symptom was oral bleeding. In both cases, the diagnosis was delayed and was made only after severe injuries were inflicted. Injuries to the oral cavity and oral bleeding of uncertain origin in infants should be considered seriously and should be carefully assessed in relation to adequacy of history to explain the mechanism of injury. When an infant has been injured and no adequate explanation is available to account for the mechanism, inflicted injury must be suspected and evaluated, so that in cases of child maltreatment, diagnosis and protection of the child from further injury can take place as early as possible. 相似文献
88.
89.
Prevention of hip fractures by external hip protectors: a randomized controlled trial 总被引:7,自引:0,他引:7
CONTEXT: Several randomized controlled trials have been performed to examine the effectiveness of external hip protectors in reducing the incidence of hip fractures, but the results are controversial. OBJECTIVE: To examine the effectiveness of hip protectors in reducing the incidence of hip fractures in an elderly high-risk population. DESIGN, SETTING, AND PARTICIPANTS: Randomized controlled trial of elderly persons aged 70 years or older, who have low bone density, and are at high risk for falls. Participants lived in apartment houses for the elderly, homes for the elderly, and nursing homes in Amsterdam and surrounding areas in the Netherlands. They were enrolled in the study between March 1999 and March 2001; the mean follow-up was 69.6 weeks. Of the 830 persons who were screened, 561 persons were enrolled. INTERVENTION: External hip protector. Both groups received written information on bone health and risk factors for falls. MAIN OUTCOME MEASURE: Time to first hip fracture. Survival analysis was used to include all participants for the time they participated. RESULTS: In the intervention group, 18 hip fractures occurred vs 20 in the control group. Four hip fractures in the intervention group occurred while an individual was wearing a hip protector. At least 4 hip fractures in the intervention group occurred late at night or early in the morning. Both in univariate analysis (log-rank P =.86) and in multivariate analysis (hazard ratio [HR], 1.05; 95% confidence interval [CI], 0.55-2.03), no statistically significant difference between the intervention group and control group was found with regard to time to first hip fracture. In addition, the per protocol analysis in compliant participants did not show a statistically significant difference between the groups (HR, 0.77; 95% CI, 0.25-2.38). CONCLUSION: The hip protector studied was not effective in preventing hip fractures. 相似文献
90.
DNA double-strand breaks (DSBs) are induced by ionizing radiation (IR) and various radiomimetic agents directly, or indirectly as a consequence of DNA repair, recombination and replication of damaged DNA. They are ultimately involved in the generation of chromosomal aberrations and were reported to cause genomic instability, gene amplification and reproductive cell death. To address the question of whether DSBs act as a trigger of apoptosis, we induced DSBs by means of restriction enzyme electroporation and compared the effect with IR in mouse fibroblasts that differ in p53 status [wild-type (+/+) versus p53-deficient (-/-) cells]. We show that (i) electroporation of PVU:II is highly efficient in the induction of DSBs, (ii) electroporation of PVU:II increases the rate of apoptosis, but not of necrosis in p53-/- cells, (iii) treatment with gamma-rays induces both apoptosis and necrosis in p53-/- cells, (iv) the frequency of DSBs correlates with the yield of apoptosis and (v) both PVU:II and gamma-ray treatment reduce the level of anti-apoptotic Bcl-2 protein in p53-/- cells whereas the level of Bax remains unaltered. Cells expressing wild-type p53 were more resistant than p53-deficient cells as to the induction of apoptosis and did not show Bcl-2 decline upon treatment with PVU:II and gamma-rays. The data provide evidence that blunt-ended DSBs induced by restriction enzyme PVU:II act as a highly efficient trigger of apoptosis, but not of necrosis. This process is related to Bcl-2 decline and does not require p53. 相似文献